A microsphere technique will be used to investigate the effects of raised intraocular pressure on the blood flow in the different parts of the optic nerve in rhesus monkeys. The possibility that increments in eye pressure may cause capillary redistribtion of the blood flow in the optic nerve resulting in underperfused areas in spite of overall normal flow rates will be investigated in cynomolgus monkeys. The procedure is to elevate the pressure in one eye and to investigate the consumption of glucose in the different parts of the retina and the optic nerve on both sides using 14C-deoxyglucose. This will be done during the period of high pressure in some experiments, in others after normalization of the eye pressure. Accumulation of radioactivity in the tissue is related to glucose consumption. Studies on the transport mechanisms involved in the nutrition of the retina will be continued. A tissue uptake technique is used in rats to investigate the presence of carrier mechanisms in the pigment epithelium and retinal capillaries. Single injection techniques with collection of retinal and uveal blood separately in pig eyes are used to disentangle the relative roles of the pigment epithelium and the retinal capillaries repsectively. The facility increasing effects of chelating agents will be analyzed further physiologically and morphologically and the possibility will be investigated to enhance this effect using ionophores.